Friday 10 February 2012 12.59 EST
First published on Friday 10 February 2012 12.59 EST

After 19 debates, eight caucuses and primaries, and tens of millions of dollars in – mostly negative – advertising, it's half-time in the Republican nomination battle. By this point, it was meant to be all over, with apparent frontrunner Mitt Romney predicted to have it wrapped by the end of January.

But his rivals – and the party's conservative base – have displayed a stubborn determination to force the contest all the way to the final play, the convention in August in Tampa, Florida.

Rick Santorum was the first to upset the script when he came from nowhere to narrowly beat Romney – eventually – in Iowa. And he was back in spectacular fashion this week, with a clean sweep of Colorado, Minnesota and Missouri. Newt Gingrich, meanwhile, enjoyed a huge victory in South Carolina that also underlined serious doubts among conservatives about Romney.

But even in a race this volatile, a few conclusions can be drawn. So now, as the candidates pause for breath and rework their strategies before the second half kicks off in Michigan and Arizona at the end of February, here are the five main lessons so far:

Momentum? What momentum?

There has never been a Republican race in which the lead has changed as often as this one. While Romney, Santorum and Gingrich have all won states, none have been able to convert this into a sustained run of victories. This is the election of the two-day wonder.

A visit to the Conservative Political Action Conference, the mega-gathering of the American right, in Washington on Thursday and Friday helps explain some of the reasons behind that volatility. Among the 5,000 or so attendees, their zest and enthusiasm is not in doubt, but it is solely for conservatism. There is no such excitement for the would-be nominees.

Romney, in particular, elicits little love, and there are few who regard Ron Paul as a viable candidate. Gingrich retains some respect from his time as House speaker. But this week, it is Santorum who is in pole position again as the non-Romney candidate.

The most frequently used buzz word at the C-Pac meeting is 'reset', reflecting the view that Santorum's victories have wiped clean everything that has gone before and a new front has opened

One of the delegates at C-Pac, Ryan Rhodes, reflecting on Santorum's wins, was one of the many to mention "reset". "I think we had had another reset. Newt Gingrich had his chance and I think we will see a major surge for Santorum.," Rhodes said.

"Conservatives are still looking for the anti-Romney candidate. You are looking at 60%-70% of the party who just do not want him."

Although Santorum has the momentum at present, Gingrich, though fading, could still come back. He could win at least Georgia and Tennessee on Super Tuesday, March 6, when 10 states are in play.

But even with Gingrich and Santorum, there are deep reservations. Asked about either, a common response is "Gingrich, but …" or "Santorum, but …". This is not an inspirational field.

The result is that all four candidates could end up taking blocs of delegates to the Tampa convention.

At present, according to the Associated Press, Romney has 107 delegates, Santorum 69, Gingrich 32 and Paul nine. A candidate needs 1,144, just over half the delegates to the convention to win.

"What we have learned is that the Republican party is in a huge mess," said Norm Ornstein, an independent political analyst at the Washington-based American Enterprise Institute, the bastion of neo-conservatism. "The candidates have one thing in common: enormous weaknesses. Mitt Romney remains a solid favourite to win the nomination but it will be a much more painful process."

Ornstein added: "Barack Obama is a very lucky man. It could not be going better for him."

Republican voters have disappeared

The biggest concern for the Republicans is the low turnout in this week's contests, as well some of the earlier ones. One of the reasons the Republican party switched from a winner-takes-all approach to the award of delegates to proportional representation was to enthuse its political base in the way the Barack Obama-Hillary Clinton battle did for the Democrats in 2008.

It has not turned out that way. The first two contests Iowa and New Hampshire saw a small increase in turnout, though mainly because of a rise in independents rather than registered Republicans. The contests since, other than South Carolina, have seen big drop-offs in voting, with Florida down 14%, Nevada down 25%, Colorado down 7% and Minnesota down 24%.

Even more worrying for Republicans, assuming Romney is the eventual nominee, is that his votes are down even on his showing in his failed bid for the party nomination in 2008.

A few months ago, polls showed enthusiasm for the White House election among Democrats was down, a worry for Obama's campaign team. That has been reversed. Enthusiasm among Republicans for the election is now down and Democratic enthusiasm is up.

Social issues have played as big as the economy

A year or two before the 2008 general election, politicians and pundits confidently predicted, with good reason, that the main issue for voters would be the Iraq war. Iraq, though, was overtaken by the collapse of the economy in September 2008.

This time round, the widely-held prediction is that election 2012 will be dominated by the economy. That is still likely to be the case, but there are already signs that as the unemployment figures and other economic indicators improve, other issues will surface too.

An early hint of this came this week in the Colorado, Minnesota and Missouri elections. The decision by one of the country's biggest cancer charities, Susan G Komen for the Cure to withdraw funding from Planned Parenthood thrust abortion and reproductive rights into centre stage. Then came the appeal court ruling that Proposition 8, the California ballot measure banning gay marriage, was unconstitutional.

And the week has ended with the White House facing a backlash from the Catholic church and the conservative right over new rules that would require health insurance plans – even those offered by Catholic hospitals and charities – to provide free birth control to female employees.

So far, the main beneficiary from this resurgence of values issues has been Santorum, whose socially conservative platform is anti-gay marriage, anti-abortion and anti-contraception. There were no exit or entrance polls to establish why Republicans voted for Santorum this week but there is anecdotal evidence that social issues were significant.

Brad Coker, head of Mason-Dixon polling, said: "They are suddenly re-emerging and Santorum is the most socially conservative. He has been consistent and if anyone was to capitalise on it, it would be him."

Super Pacs have funded a huge negative ad blitz

Super Pacs, the creation of a supreme court ruling in 2010, can raise money without restraint and with almost complete anonymity. The Romney-supporting Restore Our Future destroyed Gingrich first in Iowa and then again in Florida with multi-million dollar negative ad campaigns.

The lesson Romney learned is that negative ad campaigns work, and the latest threat to his cause, Santorum, is now likely to face the same ad blitz as Gingrich.

Gingrich has only one major backer, the Las Vegas casino/hotel owner multi-billionaire Sheldon Adelson, who may or may not continue to act as sugar daddy to his presidential ambitions.

Santorum's main backer, Foster Friess, the Wyoming investor, emerged this week, standing behind the candidate's right shoulder during his victory speech on Tuesday night.

Kathleen Hall Jamieson, professor of communication at the University of Pennsylvania's Public Policy Centre, believes that the Super Pacs, as well as the debates, have helped lengthen the process.

"Because debates have ensured candidate access to the media and voters and because single large donors have underwritten Super Pacs (as Adelson has for the pro-Gingrich one and Friess has for the one backing Santorum), candidates who might otherwise have withdrawn have remained viable long enough to brake Romney's run," she said in an email.

Romney's long-term advantage is that he is not reliant on an individual multi-millionaire but has the support of a number and, if it came to it, he could fund himself from his $200m-plus fortune.

Nobody knows anything

Possibly the single most important lesson so far. Political pundits and journalists have been consistently wrong in anticipating the ups and downs since the Republican nominating process began in earnest last August. Remember when everybody was confidently stating that the race would come down to a head-to-head between Romney and Texas governor Rick Perry?

And even after a humiliated Perry had withdrawn and limped back to Texas, the conventional wisdom had it that Romney would have the nomination in the bag by the Florida primary on January 31.

Ornstein says political journalists and pundits made the mistake of assuming Romney was the Republican heir apparent, in spite of polls showing Romney seldom getting above 25%.

They thought the conservative base "would rally round behind even though they were not thrilled by him," Ornstein said. "They underestimated the conservative movement – call it the Tea Party or whatever – and the depth of unease with Romney, and the degree to which Romney could be stupid and insecure and damage his own campaign."

Coker also recalled earlier inaccurate predictions: "Most people thought it was going to be Rick Perry and Romney going toe-to-toe."

He never subscribed to the view that the contest would be over quickly. "Anyone who thought it was going be wrapped up in January is a fool," Coker said.